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Does Pacing Make a Difference? Maybe Not

10/19/2011

Immediately on the heels of the IAAF's controversial decision to set aside women's world records set in mixed-gender races, a well-known group of South African researchers has published a study designed to determine if pacing helps runners perform better. The group hypothesized that the answer would be yes. Their results did not confirm this. Instead, pacers had a nonsignficant effect on the 5K race times of the primary subjects.

The study was interesting, though fraught by methodology issues that make its conclusion questionable, as even the authors acknowledge. The conditions seemed quite different from those in the real world of "rabbit-led" races. The study was published in the International Journal of Sports Physiology and Performance with the title: "The Effect of a Second Runner on Pacing Strategy and RPE during a Running Time Trial."

Here's what happened, brief as I can tell it. Eleven club runners with 5K times around 20 minutes ran five different 5K time trials over about a three-week period. They did the first and last entirely on their own. For the middle three time trials, there was a second runner on the indoor track. These second runners were capable of 5Ks in about 18 minutes (they were faster than the first guys). The primary subjects weren't told who the second runners were, or why they had joined the experiment. The mystery runners just showed up and joined the time trial.

So the pacers ran the middle three of the five trials. They were instructed to run slightly ahead of the first runner in one trial, slightly behind in another, and at the first runner's side in the third.

The researchers believed "that the presence of a second runner would alter the pacing strategy" of the primary subjects. They explained: "The inclusion of a second runner in the current study was intended to present an external factor that would increase the motivation of the athlete." Maybe it did or didn't, but the results showed no significant change. The primary subjects ran roughly the same in all five time-trials, starting too fast, slowing gradually through the middle miles, and then speeding up slightly toward the end. A typical pattern, in other words.

The results showed no significant differences between trials for performance, heart rate, or perceived exertion. All 11 of the primary subjects said they believed the pacers had helped them run faster, but the results (below) didn't support this. Hence the research team concluded: "These findings indicate that an athlete's subconscious pacing strategy is robust," i.e., not easy to change, and not helped by another nearby runner.

Below are the average times for the 11 runners in the five trial conditions. Apparently, a statistical analysis yielded the result of no significant differences. But looking at this chart, most of us would choose to have a pacer in front of us.

The researchers note that their experiment did not duplicate real-world racing conditions. In the real world, elite runners are provided with known pacers, told what pace these rabbits will be attempting to hit, and told that the pacers exist to help them, the elites, achieve their best efforts. In this trial, the pacers were a surprise addition to the experiment, and the primary subjects were given no instruction about who the pacers were, or what pace strategy they would follow. Perhaps a pacer is only useful if you know he or she is a "good pacer" rather than a "mystery pacer."

Or maybe pacers really and truly don't help. The problem with this notion is that it flies in the face of real-world experience, and many experts believe that real-world elite athletes and coaches are way ahead of the scientists trying to understand them.

CONDITION

5K FINISH TIME

Solo time trial

20:26

Pacer in front

19:57

Pacer in back

20:10

Pacer at side

20:24

Solo time trial

20:03

Note: The order of the three "pacer" trials were switched around so they did not always occur as shown in this table. There were 11 "primary subjects."